Sound absorbing material comprising interbonded tubular elements



S. F. REED July 11, 1967 SOUND ABSORBING MATERIAL COMPRISING INTERBONDED TUBULAR ELEMENTS 2 Sheets-Sheet 1 Filed Oct. 4. 1965 FIG. 2

FIG. 4

FIG.

INVENTOR STANLEY F. REED ATTORNEY July 11. 1967 s. F. REED 3,330,377

' SOUND ABSORBING MATERIAL COMPRISING INTERBONDED TUBULAR ELEMENTS Filed Oct. 4, 1965 2 Sheets-Sheet 2 SEVERING TUBE MAKlNG SETTING MEANS III.

sucme MEANS F IG. 5

INVENTOR STANLEY F. RE ED ATTORNEY United States Patent 3,330,377 SOUND ABSORBING MATERIAL COMPRISING INTERBDNDED TUBULAR ELEMENTS Stanley F. Reed, 4005 Brookside Road, McLean, Va. 22101 Filed Oct. 4, 1965, Ser. No. 492,670 8 Claims. (Cl. 181-33) This invention relates to acoustical products, and more particularly to a material especially suited to utilization as an acoustical tile for ceilings for various types of buildings.

Heretofore, many types of acoustical tile have been used for ceilings, but no single type of tile has been marketed which is adaptable to absorb the wide ranges of acoustic energy actually encountered in practical environments. The invention relates to constructions for improving the acoustical, thermal, and ventilating qualities of ceilings of the character indicated.

One object of the invention is to provide a ceiling having any desired predetermined sound absorption characteristics correlated to both the volume and quality of acoustic energy to be encountered, and it is a feature of the invention that this result is attained with a pleasing external surface which inherently adds to the overall appearance of the surrounding environment.

Another object is to combine readily available and inexpensive materials to provide structures having excellent acoustical properties at a minimum cost both in materials and fabrication expense. Further, because these structures have a very low density, they are adaptable to installation in the conventional manner and, in addition, allow other cheaper installation techniques that permit larger tiles and therefore involve a lower total installation expense.

Another object of this invention is to provide a ceiling structure such that, in advance of installation in a building, the acoustical characteristics of the finished building may be accurately predetermined to comply with either general or specific acoustical requirements to provide a satisfactory structure adapted to the intended utilization of the building.

Another object of the invention is to provide an acoustical ceiling structure whereby ventilation, either hot or cool air, may be passed directly through the entire ceiling structure, thus allowing the elevation or lowering of the ambient temperature of the building without direct drafts or expensive ducting.

Another object of the invention is to provide an acoustical ceiling structure of materials that are either transparent or translucent in order to provide a surface which will radiate a diffused light therethrough.

Applicants ceiling structure, having optimum acoustical properties, good light transmitting characteristics, and a porous structure to permit ventilation from a plenum thereabove has the significant advantage of eliminating many of the design problems which confront architects.

With the foregoing, and ancillary objects in view, it is proposed to effect the embodiments of the invention as follows: 1

The present invention is concerned primarily with a novel acoustical tile comprised of randomly-oriented tubular elements, These elements function individually as acoustic energy wave traps; the network of interstices therebetween acts as a more complex wave trap; and in addition, the entire resilient structure, which has a very low mass to volume ratio, acts as a porous diaphragm to absorb other wavelengths of acoustic energy. The features of improvement of the present invention over prior art structures will be readily apparent when the drawings 3,330,377 Patented July 11, 1967 appended hereto are considered in the light of the following specification.

As in the case of prior art patents, applicants structures have a multiplicity of surface irregularities which improve the absorption characteristics of the tile. However, by the use of randomly-oriented tube elements of different lengths bound together in a low-density resilient mass, the efliciency of these irregularities is greatly improved because they are interconnected by a network of interstices below the surface. Further, by utilization of the tube elements individually; the interstices therebetween; and the diaphragm action of the entire structure, the overall efiiciency of applicants tile as an acoustic absorption agent is greatly increased. In addition, applicants tube elements may be fabricated from materials having light-transmitting qualities or having a high degree of fire and flame resistance. In all of the permutations, applicants tile structures permit the eflicient transmission of ventilation from a plenum adjacent thereto, and may be surface treated with paint, plastic, or thin perforated films to improve their appearance and surface durability.

The refinements of construction and details of the functioning thereof characterizing the present invention, though not touched upon in the foregoing general outline, will be clearly understood from the following description when read in conjunction with the accompanying drawings in which:

FIGURE 1 is a front elevational view of a first embodiment of acoustic tile according to the invention, only a portion of the cut surface thereof being shown for convenience of illustration,

FIGURE 2 is a side elevational view thereof showing an uncut edge thereof,

FIGURE 3 is a front elevational view of another embodiment of acoustic tile according to the invention, a portion of the surface membrane thereof being broken away for convenience of illustration,

FIGURE 4 is a side elevational view thereof showing an uncut edge thereof, and

FIGURE 5 is a schematic diagram of an apparatus and process for forming tile as shown in FIGURE 1.

In the following description and in the claims, various details will be identified by special means for convenience, but they are intended to be as generic in their application as the art will permit.

Like reference characters denote like parts in the several figures of the drawings.

In the drawings accompanying and forming a part of this specification, certain specific disclosure of the invention is made for purposes of explanation, but it will be understood that the details thereof may be modified in various respects without departure from the broad aspect of the invention.

Referring now to the drawings, and more particularly 0 FIGURE 1, the acoustic tile shown comprises a multiplicity of tube elements 2 of the same diameter with various effective lengths. Tube elements 2 are randomly oriented and may be compacted to any degree that does not significantly distort the tubular configuration of the individual elements thereof. It will be noted that a slight deformation of adjacent tubular elements 2 may occur at points of mutual contact. A binder material 3 coats at least a significant portion of the external surface of every tube element 2. It has been found that it is unnecessary to coat the entire tubular element 2 with binder material 3 to provide optimum acoustic characteristics.

Tubes 5 from which tube elements 2 are severed may be formed of any material which will maintain a tubular configuration during and after the fabrication of tiles 1. Depending upon the intended utilization of tiles 1, these hesives have been found suitable.

.s I materials would include papers, plastics, fabrics, light metals, laminates and combinations thereof. Further,

these papers would include the most inexpensive reutilized newsprint, kraft paper, waxed paper, bagasse paper, asbestos paper, andhigh temperature papers such as fiber glass papers. Pure asbestos paper .003 to .007 inch thick slit into tapes .437 inch wide has been found to be a suitable stock to be fabricated into tubular form by conventional spiral winding machines of the automated, multiple mandrel winding head type commonly used in the soda straw industry. Further, this thin asbestos paper may be treated with an aqueous solution of magnesium chloride and subsequently treated with ammonium hydroxide to greatly increase its strength to facilitate-the fabrication of the desired tubes and the subsequent fabrication of products having improved acoustical charac teristics from these tubes. Exemplarly plastics would in elude all the thermosetting resins of the low pressure setting or forming type. Such types are well known and generally available in the art. They include resinous comounds whose polymerizing group is an allyl group, styrene, copolymers, di-allyl phthalate, bimethacrylate, acrylic base resins, urea formaldehyde, thiourea, melamine formaldehyde and aniline formaldehyde. Further, high pressure resins of the phenolic and urea types may be used. In addition, low pressure thermosetting resins may be combined with one or more thermoplastics to form a resilient material having the characteristics of the thermosetting plastics. Suitable fabrics may be formed of any type of filament, and if additional rigidity is desirable, these fabrics may be impregnated with plastic or metallized. Further, tube elements 2 may be formed of metal or ceramic having strength and thickness characteristics such that the tiles 1 fabricated therefrom would have a low mass to volume ratio, an exemplary metal would be aluminum andalloys thereof. It will be understood that tubes 5 may be fabricated from thin strips spirally wound or longitudinally lapped, from extrudable plastics or metals, or in any other manner well known in the art of tube-forming. I

Binder material 3 may be any adhesive which will bond tube elements 2 into a cohesive masseHowev er, in order to reduce the overall cost of finished tiles 1, binder ma terial 3 should have the characteristic of setting up in a short time interval in order that the tiles 1 can be sliced from'their parent mass. Elevated temperatures may be provided to reduce this setting-up time. After being sliced from their parent mass, tiles 1 may be further cured in a or tube elements 2, for instance, inexpensive commercially available'synthetic cements and synthetic resin ad- Binder material 3 may be applied to tubes 5 prior to the severing of tube elements 2 in any convenient manner, such as spraying, rolling, or stippling. It will be understood that a binder 3 can be applied to tubes 5 that will dry quickly so that tube elements 2 will be a dry mixture of binder 3. Further, binder 3 maybe applied to tube elements 2 after severing in any convenient manner, such as spraying a liquid, wetting theftubeelements 2 and of tube elements 2. In addition, when coating the external surface, further economy may be effected-by only partially coating this surface, such as by covering with stripes ordots. This will further decrease the. mass per volume of the finished products. 7

7 conventional manner. Exemplary binder materials 3 are prior to the application of. heat to effect the final setting Referring now to FIGURE 2, an edge surface of applicants acoustic product is shown. It will be noted that this surface has not been cut; is substantially rougher than the cut surface of FIGURE 1; but also has excellent acoustic absorption properties. In'the production of some types of tiles, this uncut surface may be used as the facing surface.

Referring now to FIGURES 3 and 4, another embodiment of applicants invention is shown. While the acoustic product 1 shown in FIGURES 3 and 4 comprises a mass of randomly oriented tube elements 2' held together with a binder material 3' in a manner analogous to the structure of FIGURES land 2, the tube elements 2 of this product have different diameters. 7

It will be understood that the acoustic product illustrated in FIGURES 1 and 2 includes structures of a first type comprised of tube elements wherein each element has the same length and diameter prior to severing from the parent mass, and also structures of a second type comprised of tube elements wherein each element has the same diameter, but the lengthsthereof vary. Further, it will be clear that the slicing of the parent agglomerate mass to produce acoustic tiles Would produce random length, randomly oriented tube elements in the finished product whether the lengths were originally equal or of various lengths. However, where the lengths are originally varied, the absorption characteristics of the product would be suitable for more general applications. In order to decrease the interstice volume of the acoustic product and to increase the overall strength thereof, where the lengths of tube elements 2 are varied, it has been determined that the best general products comprise approximately equal volumes of each length of tube element utilized.

Referring further to FIGURES 3 and 4, the acoustic product illustrated in FIGURES 3 and 4 includes structures of one type comprised of. tube elements wherein each element has the same length,flbut the diameters thereof vary, and another type comprised of tube elements wherein both the diameters and the lengths thereof vary. The tube lengths of the finished product would inherently be of various lengths due to the cutting of individual tubes as the .product is sliced from the parent mass. 7 In fabricating acoustic products according to the invention,.-tube diameters of one-sixteenth inch to threeeighths inch have been used. The tube lengths used have been from one-quarter inch to one and one-half inches. However, it will be understood that other diameters and lengths could be used for special applications. In combining tubes of various diameters and lengths, it has been acoustic products. These facings 12 may be of thin rigid or resilient materials either perforated or unperforated, and could serve to improve the appearance, durability, and smoothness of the finalinstallation. :Backings 13- may also be provided of rigid or resilient materials either porous or impervious, and could serve to improve the rigidity of the installation or improve the sound insulation characteristics of appl-icants products.

Referring now to. FIGURE 5, a schematic representation of one form of apparatus for producing applicants acoustic .products is shown. It will be understood that each of the devices, tube making means 4, binderapplication means 6, tube severing means 7, hopper-means 8, shaping means 9, binder setting means 10, and product severing means 11, represented by boxes in FIGURE 5, are individually well known and conventional, their combination and control'in the production of acoustic products, however, is considered novel and will be described hereinbelow. Tubes 5 are fabricated in a tube making means 4. This tube making means could be a spiral winding machine that would spiral wind tubes from thin rolls of flexible stock with either lapped or butted spiral joints; a tube forming machine which would form tubes from thin rolls of flexible stock with either lapped or butted joints oriented parallel to the longitudinal axis of the tubes formed; or an extrustion machine which would extrude tubes from raw materials, such as plastics and metals. Tubes 5 are then passed throu 1 a binder application means 6 which applies at least a partial coating of binder thereto. This could be a spraying, strippling, or rolling operation, which could entirely coat the external surface of tubes 5 with a binder material 3 or alternatively, could coat only a portion thereof. In a preferred embodiment of applicants apparatus an aqueous solution of binder material 3 is applied to tubes 5 and immediately dries to a dry surface. Tubes 5 leave binder application means 6 and pass through a tube severing means 7 wherein tubes 5 are cut into tube elements 2 of equal, controlled, or random lengths. Tube elements 2 then pass from tube severing means 7 to hopper 8. They may flow by gravity or be conveyed by any conventional means into hopper 8. Hopper 8 funnels tube elements 2 into a shaping means having the internal configuration and dimensions desired in one plane of the finished product. It will be understood that baffies, stirrers, air jets, or other means may be employed within hopper 8 to agitate tube elements 2 as they pass the-rethrough and insure that a random distribution and orientation thereof will be deposited within shaping means 9. The mass of tube elements 2 may be vibrated or screw-fed within shaping means 9 prior to being passed through binder setting means It) which sets the binder material 3 and solidifies the entire mass into a unitary structure. Binder setting means 10 may have Various forms depending upon the nature of binder material 3. If binder material 3 is a cold setting compound, only an extended length of ducting of uniform cross-section would be required. However, in a preferred embodi ment of applicants apparatus binder material 3, a quicksetting thermoplastic adhesive is utilized in conjunction with a binder setting means 10 which produces a high temperature therewithin. Heat is transmitted by direct pumping of hot air through the tube element-binder mass or by the application thereto of a powerful RF field. If hot air is to be utilized to heat the binder to a quick-setting temperature, the portion of shaping means 9 immediately inside binder settng means 10 would be porous to facilitate the application of such air. After the tube element-binder material mass is solidified in the binder setting means 10, it passes into a severing means 11 which cuts the individual acoustic products or tiles therefrom. Severing means 11 may be a conventional hori zontal band-saw or other cutting means. The acoustic tiles are conveyed in any conventional manner, either to storage or to an appropriate curing area if the binder material requires an additional curing period.

It will be understood that these completed rectangular blocks may be further shaped to provide mounting grooves, lap joints, or mounting flanges, depending upon their intended utilization. These acoustic tiles may be further processed to provide paint, anti-static coatings, or other desired surface treatments, including the lamination thereon of facings 12 or backings 13. However, an important aspect of applicants invention is that all the desired physical and acoustic characteristics can be designed into the untreated tiles by the proper selection of material from which tubes 5 are fabricated, and the careful selection of binder material 3 compatible therewith. It will be noted that a pleasing subdued surface coloration is achieved by the use of predetermined ratios of tube elements of different coordinated colors or textures. The sound absorptive properties of applicants acoustic tile result from the inherent complex damping effect; each of the random length tube elements randomly oriented within the tile acts as a small tuned chamber which transmits sound to a point within the tile, the interstices between the tube elements act as baflies to break up the sound waves traveling therethrough, the tube elements them selves absorb acoustic energy, and the entire mass of the tile, being somewhat resilient due to its very low mass to volume ratio, will have a positive diaphragm action to further enhance the overall acoustic absorption coefiicient for these acoustic products.

The invention has been described in connection with several exemplary embodiments thereof, but it is to be understood that these embodiments are given by way of illustration and not limitation; changes and modifications in the details thereof can be made by those skilled in the art without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

1. An acoustical material, comprising: a low density resilient mass consisting of a multiplicity of substantially randomly-oriented substantially cylindrical paper elements, said elements having substantially the same diameter, and at least partially coated with a binder material, and said binder material retaining said eleemnts in said randomly-oriented position.

2. An acoustical material, comprising: a low density resilient mass consisting of a multiplitcity of substantially randomly-oriented substantially cylindrical asbestos paper elements, said elements having substantially the same diameter and at least partially coated with a binder material, and said binder material retaining said elements in said randomly-oriented position.

3. An acoustical material, comprising: a low density unitary resilient cohesive mass consisting of a multiplicity of substantially randomly-oriented substantially cylindrical paper elements, said elements comprising a substantial quantity of elements having a first diameter and a substantial quantity of elements having a second diameter, said second diameter being substantially greater than said first diameter, and said elements being at least partially coated with a binder material, and said binder material retaining said elements in said randomly-oriented position.

4. An acoustical material, comprising: a low density unitary resilient cohesive mass consisting of a multiplicity of substantially randomly-oriented substantially cylindrical asbestos paper elements, said elements comprising a substantial quantity of elements having a first diameter and a substantial quantity of elements having a second diameter, said second diameter being substantially greater than said first diameter, and said elements being at least partially coated with a binder material, and said binder material retaining said elements in said randomly-oriented position.

5. An acoustical material, comprising: a low density unitary resilient cohesive mass consisting of a multiplicity of substantially randomly-oriented substantially cylindrical paper elements, said elements comprising a substantial quantity of elements having a first length and a substantial quantity of elements having a second length, said second length being substantially greater than said first length and said elements at least partially coated with a binder material, and said binder material retaining said elements in said randomly-oriented position.

6. An acoustical material, comprising: a low density unitary resilient cohesive mass consisting of a multiplicity of substantially randomly-oriented substantially cylindrical asbestos paper elements, said elements comprising a substantial quantity of elements having a first length and a substantial quantity of elements having a second length, said second length being substantially greater than said first length and said elements at least partially coated with 7 a binder material, and said binder material retaining said elements in said randomly-oriented position.

7. An acoustical material, comprising: a low density unitary resilient cohesive mass consisting of a multiplicity of substantially randomly-oriented substantially cylindrical paper elements, said elements comprising a substantial quantity of elements having a first diameter and a first length and a substantial quantity of elements having a second diameter and a second length, said second diameter being substantially difierent from said first diameter and said second length being substantially different 7 from said first length, and said elements at leastpartially coated with a binder material, and said binder material retaining said elements in said randomly-oriented position. 8. An acoustical material, comprising: a low density unitary mass consisting of a multiplicity of substantially randomly-oriented substantially cylindricalasbestos paper elements, said elements comprising a substantial quantity of elements'having a first diameter and a first length and a substantial quantity of elements having a second diameter and a second length, said second diameter being substantially diiferent from said first diameter andsaid second length being substantially diflerent from said first length, and said elements at least partially coated with a binder material, and said binder material retaining said elements in said randomly-oriented position.

References Cited UNITED STATES PATENTS 1,974,519- 9/1934 Stefiens 181-' 33 2,043,445 6/1936 OXhandler 1s1 33 2,057,731 10/1936 Munroe 61 al. 1s1 -33 2,539,904 1/1951 Hansen 131 53 FOREIGN. PATENTS 743,754 1/1933 'France. 93 ,749 4/1951 France. 1,031,122 6/1954 France.

457,787 6/1950 Italy.

20 RICHARD B. WILKINSON, Primary Examiner.

R. S. WARD, Assistant Examiner. 

1. AN ACOUSTICAL MATERIAL, COMPRISING: A LOW DENSITY RESILIENT MASS CONSISTING OF A MULTIPLICITY OF SUBSTANTIALLY RANDOMLY-ORIENTED SUBSTANTIALLY CYLINDRICAL PAPER ELEMENTS, SAID ELEMENTS HAVING SUBSTANTIALLY THE SAME DIAMETER, AND AT LEAST PARTIALLY COATED WITH A BINDER MATERIAL, AND SAID BINDER MATERIAL RETAINING SAID ELEMENTS IN SAID RANDOMLY-ORIENTED POSITION. 